# Homework Help: Dunkerley formula experiment

1. Feb 3, 2010

### no183

ok, i have just conducted a experiment regarding dunkerley formula, after that, for sure i need a report. in the report there is the use of this equation (1/f)^2=(1/f1)^2+(1/f2)^2 where f1 f2 is natural frequency of beam and lump mass(this in experiment is the motor unit which hang at center of beam) now the questions come
1) what is the condition for resonance to occur?
2) is the support for the beam make any change to the experiment? E.G simply support, pin support etc, do it have influence?
2nd experiment, continue form the first 1, then i apply a cantilever unit with 2 mass with each at a side, after that i found the distance from center for this mass on the cantilever unit using theory, then verify it via experiment, now what i can comment about this value
theoritical value is 3.15 in while experiment value is 3.35 in. and what role does cantilever unit play for?
diagram is like this
experiment 1
++++
++++
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mmmm
mmmm
experiment 2
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CUCUCU
CUCUCU
cantilever unit

--mm----------mm--
--mm----------mm--
m=mass
+=motor unit
CU=cantilever unit

*note picture not to scale both mass and motor and cantilever unit at center of beam